1. Field of the Invention
The present invention relates to a heat-sensitive stencil sheet and a process for producing it. Specifically, it relates to a heat-sensitive stencil sheet, which is excellent in a heat-sensitive and perforating property by a thermal head, a xenon process system, a flush valve system and others, and a process for producing the heat-sensitive stencil sheet.
2. Description of the Prior Art
In a prior art, a heat-sensitive stencil sheet is composed of a thermoplastic resin film such as a polyester film and a porous substrate adhered on one surface of the film with an adhesive. The heat-sensitive stencil sheet is processed by bringing a thermal head in contact with the thermoplastic resin film of the sheet, thermally melting the film by the resulting heat and forming the corresponding opening portion to the image portion of a manuscript on the sheet.
In such a stencil paper, however, an adhesive layer is formed between the thermoplastic resin film and the porous substrate in order to laminate them on each other. Therefore, there are the problems in that the film perforating property due to the heat from a thermal head is easily damaged and the adhesive layer is dissolved with the organic solvents contained in an ink at the time of printing, resulting in lowering the resistance to printing of the stencil paper. In the case of producing the stencil sheet described above, there are also other problems in that when the coated quantity of the adhesive is too much, the perforated portions in the porous substrate are buried by adhesive layers, the perforating sensitivity of the film is reduced, the ability for processing is lowered and the permeabilities of inks are decreased, and on the other hand, when the coated quantity of the adhesive is too small, the adhesion strength is low, the resistance to printing becomes bad and it is difficult to control the production processes.